what is stringlining?

learn something new every day..esp on this forum..thank u.

if the train decelerates would it tip the lighter cars to the outside?

It could.

I've only ever seen them tip to the inside, but I suspect the dynamics of real trains might be different than the models.  Truthfully, you don't have to accelerate in the curve to see this effect for a long consist at times.  Sometimes, just the weight and rolling resistance of the cars is enough to do the dirty deed, and grades will exacerbate the effect.

 

Besides trying to place the heavier cars at the front of the consist, I use only cars with very low rolling resistance in any long consist.  Older post-war cars have significantly higher rolling resistance than the modern cars with needle-point axles, and normally are problematic in a long consist. 

 

And the couplers opening on a long consist is probably a whole other topic.

 

Stringlining refers to pulling string taught, making a straight line. "String lines" are are used extensively in construction of roads, structures, etc.

 

As John described above, the cars jump the tracks  and pull to the inside of a curve trying to form a "straight line" because the front of the train and end of the train have a "tug of war" so to speak due to whatever circumstances, i.e. a derailment, excessive speed,etc.

 

Heres an H.O. video that demonstrates it:

 

I've had several string lining incidents in o gauge.  In general when going around a curve the the length of the train combined with the weight distribution of the cars causes the cars closer to the head end to jump to the inside.  Often happens with lighter cars in front and heavier cars in the back.

 

In the real world I had on incident where one of my passenger cars fell to the inside of the curve.  Officially the blame was on wide gauge track due to a particularly hot day in the spring time.  Unofficially the host rr blamed the truck assembly not pivoting freely on the passenger car.  Either way the same basic principle applied.  there was too much resistance for the car to stay on the rails properly and in jumped to the inside. 

 

If the incident happened on a long train it is possible that the first derailment could be to the inside of the curve following by the remaining derailed cars hopping to the outside.  This can all usually be prevent by proper maintenance and train handling.  Also distributed power can help prevetn string lining as well.

Nice pictures Rick!

Rick, certainly makes the point. Good learning experience. I never thought of this before.

Decelerating with excessive dynamic brakes can, and have spit the light cars right out to the outside of the curve. Same thing in model trains if you stop or slow the speed suddenly on a curve.

I don't doubt you can dump them off the outside of the curve, just that I've never had that issue, it seems more common to pull them off the inside of the curve.  I have had that problem.

I had a little layout for my students before Christmas, complete with a Lionel 316 bridge. They stacked the boxes in the gondola too high, and it jammed under the bridge. That caused some impressive stringlining, not to mention one stuck gondola!

On a low speed freight only line curve problems, string-lining, flange wear, drag and rail head wear, can all be decreased by using negative elevation.

It is not a good idea to super elevate curves on a model railroad.  Properly weighting all of your rolling stock to NMRA standards also helps to prevent stringlining.  Making speed changes gradually also helps.

.....

Dennis

There are two areas of my layout where I really messed up, tight turns and a significant grade. I've learned to live with it and pretty much know what will and will not make the grade without stringlining. A rookie mistake that will take a significant amount of work to fix.

Dennis, I have not tried weighting the cars to standards. I think I will give that a shot. Good reminder for me. Thanks.

I agree.  Probably could be made to happen by deliberately stopping a long heavy train suddenly in the middle of a curve - at least one without flywheels, but I think that flywheels and common sense operation would prevent that in all cases.

 

I used to have stringlining routinely in N guage, when I would run really long (18 car) versions of the Super Chief, but I have had only one case of stringlining in all my O gauge experience: when I first tried to run my "War Train" 24+  flatcars, many with very heavy diecast armor on them - it stringlined badl, pulling them off on the inside.  I simple moved the heaviest stuff up front and all the plastic models and so and so to the rear of the train.  Problem solved. 

There are two areas of my layout where I really messed up, tight turns and a significant grade. I've learned to live with it and pretty much know what will and will not make the grade without stringlining. A rookie mistake that will take a significant amount of work to fix

 

Congratulation, you now have a great setup for a contract pusher service.  I call my contract pusher service "Hire Power"  "Can't get over the top? Call a Hire Power".

 

You need a siding far enough from the grade to get the pusher behind the train.  I use repainted Atlas Amtrak toasters, which are cheap and have their own totally independent control.  Break the knuckle off.

 

Hills and stringlining - no problem. Plus you can't believe how much fun you'll have, if you can get the control away from the Kids.